In Django 3.2 before 3.2.20, 4 before 4.1.10, and 4.2 before 4.2.3, EmailValidator and URLValidator are subject to a potential ReDoS (regular expression denial of service) attack via a very large number of domain name labels of emails and URLs.

In Django 3.2 before 3.2.16, 4.0 before 4.0.8, and 4.1 before 4.1.2, internationalized URLs were subject to a potential denial of service attack via the locale parameter, which is treated as a regular expression.